Respiratory Pathology — MCQs

Respiratory Pathology Indian Medical PG Practice Questions and MCQs

Question 271: Which of the following statements about small cell carcinoma of the lung is incorrect?

A. It is a poorly differentiated neuroendocrine tumor.
B. It usually presents as a central mass.
C. Cells show a salt and pepper chromatin pattern.
D. It is less associated with paraneoplastic syndromes compared to non-small cell lung cancers. (Correct Answer)

Explanation: **Explanation** Small cell carcinoma (SCLC) is a highly aggressive, poorly differentiated neuroendocrine tumor [1]. The correct answer is **D** because SCLC is actually **more frequently associated with paraneoplastic syndromes** than any other lung cancer [1]. **Why Option D is incorrect (and thus the right answer):** SCLC originates from neuroendocrine (Kulchitsky) cells, which have the metabolic machinery to secrete ectopic hormones. It is classically associated with: * **SIADH** (Syndrome of Inappropriate Antidiuretic Hormone) * **Ectopic ACTH secretion** (leading to Cushing Syndrome) [1] * **Lambert-Eaton Myasthenic Syndrome** (antibodies against voltage-gated calcium channels) **Analysis of other options:** * **Option A:** SCLC is defined as a high-grade, **poorly differentiated neuroendocrine tumor** [2]. It expresses markers like Chromogranin A, Synaptophysin, and CD56 [2]. * **Option B:** It typically arises in the major bronchi, presenting as a **central/hilar mass** with frequent mediastinal lymphadenopathy [2]. * **Option C:** Microscopically, the cells have scant cytoplasm and nuclei with finely granular, "open" chromatin, classically described as **"salt and pepper" chromatin** [2]. **High-Yield NEET-PG Pearls:** 1. **Azzopardi Effect:** Basophilic staining of vessel walls due to DNA encrustation from necrotic tumor cells (highly characteristic of SCLC). 2. **Smoking Link:** SCLC has the strongest association with cigarette smoking. 3. **Genetics:** Nearly 100% of cases show mutations in **TP53** and **RB1** genes. 4. **Treatment:** Unlike Non-SCLC, SCLC is usually disseminated at diagnosis and is treated primarily with chemotherapy/radiotherapy rather than surgery [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 725-727. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 337-338.

Question 272: Bronchial hyperplasia may be caused by all of the following except?

A. Smoking
B. Theophylline (Correct Answer)
C. Prematurity
D. Allergy

Explanation: **Explanation:** The question asks for the factor that does **not** cause bronchial hyperplasia. Bronchial hyperplasia (specifically of the goblet cells and smooth muscle) is a reactive structural change in the airway in response to chronic irritation or developmental stressors. **Why Theophylline is the correct answer:** **Theophylline** is a methylxanthine derivative used as a bronchodilator in asthma and COPD. Its primary mechanism involves inhibiting phosphodiesterase (PDE), leading to increased cAMP levels, which results in **smooth muscle relaxation**. It does not induce cellular proliferation or hyperplasia; rather, it is used to treat the symptoms resulting from airway narrowing. **Analysis of incorrect options:** * **Smoking:** Chronic inhalation of tobacco smoke is a potent irritant [1]. It leads to **Goblet cell hyperplasia** and mucus gland hypertrophy (Reid Index > 0.4) as a protective mechanism, characteristic of Chronic Bronchitis [1]. * **Prematurity:** Premature infants often require mechanical ventilation and oxygen therapy, leading to **Bronchopulmonary Dysplasia (BPD)**. A hallmark of BPD is the hyperplasia of bronchial smooth muscle and peribronchial fibrosis. * **Allergy:** Chronic allergic stimulation (as seen in Bronchial Asthma) triggers a remodeling process [2]. This includes **smooth muscle hyperplasia** and hypertrophy driven by inflammatory mediators like IL-4 and IL-13 [2]. **High-Yield NEET-PG Pearls:** * **Reid Index:** Ratio of the thickness of the mucous gland layer to the thickness of the wall between the epithelium and cartilage. It increases (>0.4) in chronic bronchitis due to glandular hyperplasia [1]. * **Curschmann Spirals & Charcot-Leyden Crystals:** Classic microscopic findings in the sputum of patients with allergic asthma. * **Airway Remodeling:** In asthma, this involves subepithelial fibrosis (thickening of the basement membrane), goblet cell hyperplasia, and smooth muscle hyperplasia [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 685-686. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 688-690.

Question 273: Following thoracotomy, a lesion is detected in the right lower lung lobe of a 20-year-old man. The lesion is found to be nonfunctioning lung tissue served by vessels separate from those of the adjacent lung tissue. What is the most likely diagnosis?

A. Mesothelioma
B. Hiatal hernia
C. Glomus tumor
D. Bronchopulmonary sequestration (Correct Answer)

Explanation: ### Explanation **Correct Answer: D. Bronchopulmonary Sequestration** The clinical presentation describes the classic features of **Bronchopulmonary Sequestration (BPS)**. BPS is a congenital anomaly characterized by a mass of nonfunctioning lung tissue that lacks a normal connection to the tracheobronchial tree and, crucially, receives its **blood supply from systemic arteries** (usually the thoracic or abdominal aorta) rather than the pulmonary arteries. There are two types: 1. **Extralobar:** The mass is outside the visceral pleura (often in the lower lobe or diaphragm) and is common in infants [1]. 2. **Intralobar:** The mass is within the visceral pleura of a lung lobe and often presents in older children or young adults due to recurrent infections or bronchiectasis [1]. **Why Incorrect Options are Wrong:** * **A. Mesothelioma:** A malignant tumor of the pleura strongly associated with asbestos exposure. It presents as pleural thickening or effusion, not as a discrete mass of nonfunctioning lung tissue with systemic blood supply. * **B. Hiatal Hernia:** This involves the protrusion of the stomach through the esophageal hiatus of the diaphragm into the mediastinum. It is not composed of lung tissue. * **C. Glomus Tumor:** A benign, highly vascularized tumor arising from the glomus body (involved in temperature regulation), typically found in the subungual region (under fingernails), not the lung parenchyma. **NEET-PG High-Yield Pearls:** * **Key Diagnostic Feature:** Systemic arterial supply (Aorta) is the "gold standard" for identifying sequestration on imaging (CT Angiography). * **Location:** Most commonly found in the **left lower lobe** (though the question specifies the right, the pathology remains the same). * **Extralobar Sequestration** is frequently associated with other congenital anomalies, most commonly **congenital diaphragmatic hernia** [1]. * **Intralobar Sequestration** usually presents later in life with localized bronchiectasis or recurrent pneumonia [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 677-679.

Question 274: Rasmussen's aneurysm occurs due to which artery?

A. Vertebral artery
B. Bronchial artery
C. Pulmonary artery (Correct Answer)
D. Posterior intercostal artery

Explanation: **Explanation:** **Rasmussen’s aneurysm** is a clinical phenomenon associated with **chronic cavitary pulmonary tuberculosis**. It refers to an inflammatory pseudoaneurysm of a **pulmonary artery** branch located in the wall of a tuberculous cavity. 1. **Why Pulmonary Artery is Correct:** In chronic tuberculosis, the progressive inflammation and necrosis (caseation) within a lung cavity lead to the thinning and weakening of the adjacent pulmonary arterial wall. As the lung parenchyma is destroyed, the arterial wall loses its structural support and bulges, forming an aneurysm. If this aneurysm ruptures into the cavity, it leads to massive, life-threatening hemoptysis. 2. **Why Other Options are Incorrect:** * **Bronchial Artery:** While bronchial arteries are the most common source of *general* hemoptysis (due to their high systemic pressure), they are not the anatomical site of a Rasmussen’s aneurysm. * **Vertebral Artery:** This artery supplies the brain and spinal cord; it has no anatomical involvement in pulmonary cavitary lesions. * **Posterior Intercostal Artery:** These supply the chest wall and pleura. While they may develop collateral circulation in chronic pleural diseases, they are not involved in the formation of Rasmussen’s aneurysms. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Presentation:** A patient with a history of treated or chronic TB presenting with sudden, voluminous hemoptysis. * **Location:** Usually occurs in the upper lobes (where TB cavities are most common). * **Radiology/Management:** Contrast-enhanced CT (CECT) is the diagnostic tool of choice. The definitive management is often **bronchial or pulmonary artery embolization** or emergency surgery. * **Pathology Note:** It is a *pseudoaneurysm* because the wall is composed of fibrous tissue rather than all three layers of the blood vessel.

Question 275: Which of the following are histological features of pulmonary hypertension?

A. Thrombi in pulmonary vasculature and vaso-occlusive disease and arterial wall thickening (Correct Answer)
B. Capillaritis of alveolar septa and vaso-occlusive disease and arterial wall thickening
C. Saddle thrombi in pulmonary trunk and vaso-occlusive disease and arterial wall thickening
D. Capillaritis of alveolar septa and vaso-occlusive disease and arterial wall thickening

Explanation: **Explanation:** Pulmonary Hypertension (PH) is characterized by a progressive increase in pulmonary vascular resistance, leading to structural remodeling of the pulmonary arteries [1]. **1. Why Option A is Correct:** The hallmark of PH involves a triad of structural changes: * **Arterial Wall Thickening:** Chronic high pressure leads to **medial hypertrophy** (smooth muscle proliferation) and **intimal fibrosis** [1]. * **Vaso-occlusive Disease:** In advanced stages (especially Group 1 PAH), "Plexiform lesions" form—these are glomeruloid-like tufts of proliferating endothelial cells that obstruct the lumen. * **Thrombi in Vasculature:** Stasis and endothelial dysfunction lead to **in-situ thrombosis** within small pulmonary arteries, further narrowing the vascular bed [1]. **2. Why Other Options are Incorrect:** * **Options B & D (Capillaritis):** Capillaritis (inflammation of the alveolar capillaries) is a feature of **Diffuse Alveolar Hemorrhage (DAH)** syndromes, such as Goodpasture syndrome or Granulomatosis with Polyangiitis (GPA), not typical PH. * **Option C (Saddle Thrombi):** A saddle thrombus is a large embolus lodged at the bifurcation of the pulmonary trunk, causing **acute** right heart failure (Cor Pulmonale). While it causes a sudden spike in pressure, it is a macro-vascular embolic event rather than a chronic histological feature of PH remodeling [1]. **Clinical Pearls for NEET-PG:** * **Plexiform Lesions:** Pathognomonic for severe, advanced Pulmonary Arterial Hypertension (PAH). * **Heath-Edwards Grading:** A 6-stage histological grading system used to assess the severity of PH (Grade 1: Medial hypertrophy; Grade 6: Necrotizing arteritis). * **BMPR2 Mutation:** The most common genetic cause of heritable PAH (leads to smooth muscle proliferation). * **Right Ventricular Hypertrophy:** The primary cardiac consequence of chronic PH, eventually leading to **Cor Pulmonale** [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, p. 707.

Question 276: Which of the following statements is NOT true regarding Bronchoalveolar carcinoma?

A. It is a type of Adenocarcinoma.
B. It involves stromal invasion with desmoplasia. (Correct Answer)
C. It shows preservation of the alveolar structure.
D. It grows along pre-existing anatomical structures.

Explanation: **Explanation:** **Bronchoalveolar Carcinoma (BAC)**, now classified under the spectrum of **Adenocarcinoma in situ (AIS)** and **Minimally Invasive Adenocarcinoma (MIA)**, is unique because of its non-invasive growth pattern. [1] 1. **Why Option B is the correct answer (The "False" statement):** The hallmark of BAC is its **lepidic growth pattern**, meaning the tumor cells "crawl" along the pre-existing alveolar walls without invading the underlying stroma, blood vessels, or pleura. [1] Because there is no stromal invasion, there is **no desmoplastic response** (fibrotic reaction). If stromal invasion or desmoplasia is present, the diagnosis shifts to invasive adenocarcinoma. 2. **Analysis of Incorrect Options:** * **Option A:** BAC is a subtype of **Adenocarcinoma**. [1] It arises from peripheral lung tissue, specifically from Clara cells or Type II pneumocytes. * **Option C & D:** These describe the **Lepidic pattern**. The tumor uses the alveolar septa as a scaffold, preserving the basic lung architecture. [1] This preservation is why BAC often appears as a "ground-glass opacity" or mimics pneumonia on a chest X-ray. **High-Yield Clinical Pearls for NEET-PG:** * **Location:** Always peripheral. * **Radiology:** Can present as a single nodule, multiple nodules, or a diffuse "pneumonic" infiltrate. * **Microscopy:** Look for the "butterflies on a fence" appearance (cells lining alveolar walls). [1] * **Prognosis:** It has a significantly better prognosis than other bronchogenic carcinomas because of its non-invasive nature. * **Smoking:** It is the subtype least strongly associated with smoking and is the most common lung cancer found in non-smoking women. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 721-723.

Question 277: High Reid index is indicative of which disease?

A. Pulmonary tuberculosis
B. Bronchial asthma
C. Chronic bronchitis (Correct Answer)
D. Emphysema

Explanation: ### Explanation **Correct Answer: C. Chronic Bronchitis** The **Reid Index (RI)** is a pathological measurement used to quantify the hypertrophy of mucus-secreting glands in the airways [1]. It is defined as the ratio of the **thickness of the submucosal gland layer** to the **total thickness of the bronchial wall** (measured from the epithelium to the inner surface of the perichondrium). * **Normal Value:** < 0.4 (or less than 40% of the wall thickness). * **In Chronic Bronchitis:** Chronic irritation (usually from smoking) leads to hyperplasia and hypertrophy of the submucosal glands to produce more mucus [1]. This increases the RI, typically to **> 0.5**. --- ### Why the other options are incorrect: * **A. Pulmonary Tuberculosis:** This is a granulomatous infectious disease characterized by Caseating necrosis and Langhans giant cells. It does not primarily involve glandular hypertrophy of the bronchial wall. * **B. Bronchial Asthma:** While asthma involves mucus plugging and goblet cell hyperplasia, the hallmark pathological features are Curschmann spirals, Charcot-Leyden crystals, and thickening of the basement membrane, rather than a significantly elevated Reid Index. * **D. Emphysema:** This is defined by the permanent enlargement of airspaces distal to the terminal bronchioles due to alveolar wall destruction [2]. It is a disease of the lung parenchyma, not the bronchial glands [3]. --- ### NEET-PG High-Yield Pearls: 1. **Clinical Definition of Chronic Bronchitis:** Productive cough for at least **3 consecutive months** in at least **2 consecutive years**. 2. **Reid Index Calculation:** (Gland thickness) / (Wall thickness). Note: It excludes the surface epithelium and the cartilage. 3. **Microscopic Hallmark:** The most characteristic feature of chronic bronchitis is the increase in size (hypertrophy) of the tracheobronchial mucous glands [1]. 4. **Blue Bloaters:** Patients with chronic bronchitis are often referred to as "Blue Bloaters" (hypoxia/cyanosis + edema), whereas emphysema patients are "Pink Puffers." **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 685-686. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 684-685. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 326-327.

Question 278: Which of the following statements are true regarding the pathogenesis of bronchitis?

A. Initiating factor is exposure to noxious stimuli or tobacco.
B. Hypersecretion of mucus in large airways.
C. Inflammatory infiltrate.
D. All of the above. (Correct Answer)

Explanation: **Pathogenesis of Chronic Bronchitis** Chronic bronchitis is defined clinically as a persistent cough with sputum production for at least 3 months in at least 2 consecutive years. Its pathogenesis is a classic example of the lung's response to chronic irritation. **Explanation of Options:** * **Option A (Initiating Factor):** The primary trigger is chronic irritation by inhaled substances. **Tobacco smoke** is the most common culprit (90% of cases), followed by grain, cotton, or silica dust [1]. These irritants trigger an inflammatory response and oxidative stress. * **Option B (Mucus Hypersecretion):** This is the hallmark of the disease. Chronic irritation leads to **hypertrophy of submucosal glands** in the trachea and bronchi, and an increase in **goblet cells** in smaller airways. This results in the characteristic "mucus plugs." * **Option C (Inflammatory Infiltrate):** Persistent irritation causes the recruitment of neutrophils, macrophages, and T-lymphocytes [1]. This chronic inflammation leads to fibrosis of the small airways (bronchiolitis obliterans), further contributing to airflow obstruction [1]. Since all three processes—irritant exposure, mucus gland hypertrophy, and chronic inflammation—are integral to the disease process, **Option D is the correct answer.** **High-Yield NEET-PG Pearls:** * **Reid Index:** The gold standard pathological finding. It is the ratio of the thickness of the submucosal gland layer to the thickness of the wall between the epithelium and cartilage. **Normal < 0.4; Chronic Bronchitis > 0.5.** * **Blue Bloaters:** Patients are often cyanotic and edematous (due to right heart failure/cor pulmonale), distinguishing them from "Pink Puffers" (Emphysema). * **Small Airway Disease:** While mucus hypersecretion occurs in large airways, the earliest physiological change is often seen in the small airways (bronchioles) [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 685-686.

Question 279: Carcinoid tumors typically develop from which of the following cell types?

A. Enterochromaffin cells (Correct Answer)
B. Neuroectoderm
C. J cells
D. Goblet cells

Explanation: **Explanation:** Carcinoid tumors are well-differentiated neuroendocrine neoplasms that arise from the **Enterochromaffin (EC) cells** (also known as Kulchitsky cells) [1]. These cells are part of the Diffuse Neuroendocrine System (DNES) and are normally found scattered throughout the bronchial epithelium and the gastrointestinal tract [2]. They are characterized by their ability to produce, store, and secrete amines and polypeptide hormones, such as serotonin (5-HT) [1], [2]. **Analysis of Options:** * **Enterochromaffin cells (Correct):** These are the progenitor cells for carcinoid tumors. On electron microscopy, they show characteristic **dense-core neurosecretory granules** [1]. * **Neuroectoderm:** While neuroendocrine cells share some functional similarities with neurons, carcinoid tumors arise from endoderm-derived epithelial cells that have acquired neuroendocrine differentiation, not directly from the neuroectoderm (which gives rise to the CNS and melanocytes). * **J cells:** These are "Juxtacapillary" receptors in the alveolar walls involved in the reflex response to pulmonary congestion; they have no relation to carcinoid tumorigenesis. * **Goblet cells:** These are mucus-secreting cells. Tumors arising from these are typically adenocarcinomas, not neuroendocrine tumors. **High-Yield Clinical Pearls for NEET-PG:** * **Histology:** Classic "organoid" pattern with nests, cords, or trabeculae of uniform cells with **"salt and pepper"** chromatin [1]. * **Markers:** Positive for **Chromogranin A**, **Synaptophysin**, and CD56. * **Carcinoid Syndrome:** Occurs in <10% of patients (usually with liver metastasis). Symptoms include flushing, diarrhea, and right-sided valvular heart lesions [1]. * **Location:** The most common site in the GI tract is the **appendix** (often an incidental finding), but the **ileum** is the most common site to cause carcinoid syndrome [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 780-782. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, p. 727.

Question 280: A Pancoast tumor is typically associated with cancer of which of the following structures?

A. Apical lobe of the lung (Correct Answer)
B. Lingula of the lung
C. Thyroid gland
D. Pyriform fossa

Explanation: **Explanation:** **Pancoast tumor**, also known as a **superior sulcus tumor**, refers to a malignancy (most commonly **Squamous cell carcinoma** [1] or Adenocarcinoma [1]) located at the extreme apex of the lung. 1. **Why Option A is correct:** The tumor arises in the **apical lobe** and extends superiorly to involve the thoracic inlet. Its clinical significance lies in its proximity to vital structures like the brachial plexus and the sympathetic chain [1], rather than the pulmonary symptoms (like cough) usually seen in other lung cancers. 2. **Why the other options are incorrect:** * **Option B (Lingula):** The lingula is a part of the left upper lobe but is anatomically equivalent to the middle lobe and is located inferiorly, far from the superior sulcus. * **Option C & D (Thyroid & Pyriform fossa):** While these are located in the neck/upper aerodigestive tract and can cause local compression, they do not constitute a "Pancoast tumor," which is specifically defined as a primary bronchogenic carcinoma. **Clinical Pearls for NEET-PG:** * **Pancoast Syndrome:** Characterized by the triad of: 1. **Horner’s Syndrome:** Due to involvement of the **cervical sympathetic chain/stellate ganglion** (Ptosis, Miosis, Anhidrosis) [1]. 2. **Brachial Plexopathy:** Specifically the lower trunk (**C8–T1**), leading to pain and weakness in the ulnar distribution of the arm and wasting of intrinsic hand muscles [1]. 3. **Rib Destruction:** Erosion of the first and second ribs [1]. * **Most common histological type:** Squamous cell carcinoma (historically) [1], though Adenocarcinoma is now frequently reported. * **Initial Investigation:** Chest X-ray (shows apical capping/mass); **MRI** is the gold standard for assessing local invasion before surgery. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 334-337.

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Congenital Anomalies

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Lung Tumors

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Pleural Diseases

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Interstitial Lung Diseases

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Occupational Lung Diseases

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